This invention relates to the field of fuel oil filters for diesel engines, and in particular to protective devices that keep the new filter clean between the time it is removed from the manufacturer's package and installed on the diesel engine.
When a new fuel filter is to replace an old one on a diesel engine, the new filter has to be primed by filling with diesel fuel. It is important that such priming diesel fuel, which may contain some dirt and contaminants, is poured into the filter on the up-stream side of the filtering material, and that none of it is poured into the central cavity of the filter which is on the downstream side. To accomplish this, the present invention comprises a removable cap placed over the open working end of the filter which has a plug that seats in the entrance to the central cavity of the filter to prevent any of the priming diesel fuel from getting into the central cavity on the downstream side of the filtering material. The removable cap includes a series of circumferentially spaced apart apertures which open to the filter cavity on the upstream side of the filtering material. Thus, the filter can be filled with priming diesel fuel which has to pass through the filtering material to filter out any dirt or contaminants which could otherwise reach and damage the fuel pump when the new filter is installed on the engine.
The inventor does not know of any prior art devices of this kind for use with diesel fuel filters and diesel engines. A search revealed an accessory for coffee percolators disclosed in U.S. Pat. No. 2,953,985 which prevents coffee from getting down the central stem of the percolator, a filler fixture for use in pouring explosive material into hand grenades as disclosed in U.S. Pat. No. 2,360,914, and U.S. Pat. No. 2,122,216 discloses a bulk dispensing device for measuring pulverulent household materials such as coffee.